Research/Terra/ 129699
Task evidence / water-feature-selection

Lakes near Canada's mapped boundary

PassComputational taskUnpublished draft
Download evidence JSON ↓

The question

129699
How many lakes are within 10 km of the Canadian border?
Exact submitted task and declared adaptations
How many lakes are within 10 km of the Canadian border?

Task conventions: Use all original CEC lake/reservoir polygons and the original country polygons with NAME_EN exactly Canada. The frozen interpretation of border is Canada's complete mapped polygon boundary, including coasts and islands, not just its international land boundary. Measure shortest planar distance from each entire lake geometry to the Canadian polygon boundary after transforming original vertices to EPSG:3978, strictly less than 10000 metres. This corrects the reference's buffered-polygon overlaps operation, which is not distance to a border. Do not replace lake polygons by centroids, silently include every interior Canadian lake, densify or simplify. Explicitly make-valid invalid lake polygons for measurement using linework in the original source CRS, retaining all polygon components; retain original IDs and geometry in the selected output. This is a generalized projected screening approximation, not a surveyed international-boundary calculation. Count original lakes once; all supplied lake/reservoir types count as the inventory. Unknown_count is missing/empty original lake geometry. Source and derived data are internal benchmark only.



Return an inspectable selected-feature artifact preserving original attributes, geometry and benchmark_row_id. End with one fenced JSON object: {count:integer,unknown_count:integer,coverage_note:string,selection:{collectionId,itemId,assetKey}}. Map optional. State the boundary interpretation and projected distance limitation.

Delivery format: provide the answer object with all fields specified above as final_response on assess_result, alongside the inspected final artifact_refs. This replaces the JSON-code-block formatting requirement above. Blue attaches your explicit selection to the accepted final answer. Finish with a concise ordinary-language answer agreeing with that selected result; do not duplicate the JSON in chat.

Supplied immutable inputs:
[
  {
    "name": "North American lakes, CEC 2023 frozen benchmark source",
    "edition": "CEC North American Environmental Atlas version 4.0 (2023), original benchmark snapshot; benchmark-only use",
    "units": {},
    "collectionId": "blue-generated--[resource id withheld]",
    "itemId": "[resource id withheld]",
    "assetKey": "data"
  },
  {
    "name": "World Bank country boundaries",
    "edition": "GeoBenchX harmonized names",
    "units": {},
    "collectionId": "blue-generated--[resource id withheld]",
    "itemId": "[resource id withheld]",
    "assetKey": "data"
  }
]

Outcome & verification

Independent artifact and delivery checks passed.

Duration
22m 2s
Recorded Blue tool calls
53
Total tokens
2,218,182
Model cost
Not recorded
Application revision
d50497ea9084f29c91b05406688f87035df98d8a
Release
terra-geobenchx-v1

Recorded final answer

I found **581** lake/reservoir polygons within 10 km of **Canada’s complete mapped polygon boundary**, including coasts and islands. **Unknown_count is 0.** This uses the supplied CEC 2023 lake/reservoir benchmark snapshot and the supplied World Bank/GeoBenchX country polygons, retrieved on **2026-10-07**. The distance is the shortest **planar EPSG:3978** boundary distance, so it is a **projected screening approximation**, not a surveyed or geodesic legal-boundary measurement. ### Limitations - The result is limited to the supplied frozen CEC lake/reservoir inventory and the supplied harmonized country polygons. - Projected planar distance in EPSG:3978 is an approximation and can differ from geodesic or legal boundary measurements. - Boundary means the complete mapped polygon boundary of the supplied Canada multipolygon, including coasts and islands, not only the international land boundary. - Distances are shortest 2D planar distances in EPSG:3978 after transforming original vertices, so this is a projected screening approximation, not a surveyed or geodesic legal-boundary measurement. - The result is limited to the supplied frozen CEC lake/reservoir benchmark inventory and the supplied harmonized country polygons. - Frozen benchmark inventory only. - Supplied harmonized country polygon only. - Projected planar screening in EPSG:3978. - Linework make-valid is for measurement only; output geometry remains the original source geometry.

Independent checks

These checks are separate from the agent's own assessment. A successful job or an assertion of success is not enough to pass.

Expected count
581
Reported count
581
Computation verified
Yes
Answer fulfilled
Yes
Full grading and rubric record
{
  "expectedCount": 581,
  "actualCount": 581,
  "expectedMetrics": null,
  "actualMetrics": null,
  "computationCorrect": true,
  "answerFulfilled": true,
  "adjudication": null,
  "qualification": null,
  "reasons": []
}

Recorded investigation findings

The agent's reported hypotheses and assessments, retained as evidence of its process—not independent proof that the answer is correct. Failed calls retain their requested verdict, not an accepted assessment.

run_trial · completed

Does a full-inventory workflow using NAME_EN='Canada', targetGeometry='boundary', EPSG:3978 distance, and onInvalidSource='make-valid' produce the requested near-border lake selection without centroid or buffer shortcuts?

assess_trial · completed · assessment: sufficient

The trial used the supplied country polygon filtered to NAME_EN exactly Canada and produced one valid Canada MultiPolygon with 410 parts, matching the requested full mapped polygon including coasts and islands. The vector-nearest-distance summary confirms boundary mode, distanceCrs EPSG:3978, onInvalidSource make-valid, onInvalidTargets error, targetCount 1, sourceCount 13135, measuredSourceCount 13135, unknownSourceCount 0, and repairedSourceCount 5. The distance result preserved 13,135 lake rows and original lake fields plus dist_canada_boundary_m in metres. Filtering dist_canada_boundary_m < 10000 produced 581 selected rows. The selected artifact has 581 distinct benchmark_row_id values, so the selected original lakes are counted once each. The selected distances range from 0.0 to 9999.358033808905 metres, which matches the strict less-than threshold.

assess_result · completed · assessment: sufficient

The completed final workflow selected 581 original lake and reservoir polygons whose shortest planar distance to the boundary of the single supplied Canada multipolygon is strictly less than 10,000 metres. The selected artifact preserves original source geometry, original source attributes, and benchmark_row_id, and includes dist_canada_boundary_m for inspection. The completed final count table reports 581 selected lakes, and the completed final unknown-count table reports 0 rows with missing or empty original geometry. The completed final distance summary confirms EPSG:3978, boundary-mode distance, linework make-valid for invalid lake measurement only, and 5 repaired source geometries.

Recorded workflow

  1. 01

    Filter Canada

    Recorded vector-filter · succeeded

  2. 02

    Country boundaries benchmark

    Recorded source · succeeded

  3. 03

    Lakes within 10 km of Canada's full mapped boundary

    Recorded output · succeeded

  4. 04

    Selected lake count

    Recorded output · succeeded

  5. 05

    Unknown geometry count

    Recorded output · succeeded

  6. 06

    Measure lake distance to Canada boundary

    Recorded vector-nearest-distance · succeeded

  7. 07

    CEC lakes benchmark

    Recorded source · succeeded

  8. 08

    Select lakes within 10 km

    Recorded vector-filter · succeeded

  9. 09

    Count selected lakes

    Recorded table-group-statistics · succeeded

  10. 10

    Count unknown rows

    Recorded table-group-statistics · succeeded

  11. 11

    Select unknown geometry rows

    Recorded vector-filter · succeeded

  12. 12

    Filter Canada

    Recorded vector-filter · succeeded

  13. 13

    Country boundaries benchmark

    Recorded source · succeeded

  14. 14

    Measure lake distance to Canada boundary

    Recorded vector-nearest-distance · succeeded

  15. 15

    CEC lakes benchmark

    Recorded source · succeeded

  16. 16

    Select lakes within 10 km

    Recorded vector-filter · succeeded

  17. 17

    Count selected lakes

    Recorded table-group-statistics · succeeded

  18. 18

    Count selected lakes

    Recorded output · succeeded

  19. 19

    Count unknown rows

    Recorded output · succeeded

  20. 20

    Count unknown rows

    Recorded table-group-statistics · succeeded

  21. 21

    Select unknown geometry rows

    Recorded vector-filter · succeeded

Activity

Recorded actions

Recorded observable actions only, not private reasoning. Raw payloads, geometry, private links and credentials are omitted; full evidence is retained privately. Activity/workflow lists bounded at 500 entries.

  1. Progress update

    I’m checking the retained analysis state and the supplied benchmark sources first, then I’ll test the exact border-distance method on a small private slice before I run the full count.

  2. get_analysis

    Recorded tool call · completed

  3. Progress update

    I’ve got a clean slate, so I’m inspecting the two supplied benchmark sources next: first the lake and country schemas, then the processor options needed for make-valid, boundary extraction, projection, distance screening, and counting.

  4. get_collection

    Recorded tool call · completed

  5. get_collection

    Recorded tool call · completed

  6. get_item

    Recorded tool call · completed

  7. get_item

    Recorded tool call · completed

  8. Progress update

    I found the exact source fields I need: `NAME_EN` on countries and `benchmark_row_id` on both datasets. I’m sampling the supplied rows now to confirm the lake inventory fields and the Canada name value before I choose the processing graph.

  9. get_collection

    Recorded tool call · completed

  10. get_collection

    Recorded tool call · completed

  11. update_analysis_brief

    Recorded tool call · completed

  12. list_processors

    Recorded tool call · completed

  13. list_processors

    Recorded tool call · completed

  14. describe_processors

    Recorded tool call · completed

  15. describe_processors

    Recorded tool call · completed

  16. Progress update

    I found a strong direct method: `vector-nearest-distance` already measures exact polygon-to-polygon-boundary distance in a projected CRS, keeps original lake geometry, and reports unknown geometry separately. I’m pulling the exact trial and proposal syntax now so I can test that method cleanly instead of approximating it with buffers.

  17. get_tool_help

    Recorded tool call · completed

  18. get_tool_help

    Recorded tool call · completed

  19. get_tool_help

    Recorded tool call · completed

  20. get_tool_help

    Recorded tool call · completed

  21. get_tool_help

    Recorded tool call · completed

  22. get_tool_help

    Recorded tool call · completed

  23. get_tool_help

    Recorded tool call · completed

  24. get_tool_help

    Recorded tool call · completed

  25. get_tool_help

    Recorded tool call · completed

  26. get_tool_help

    Recorded tool call · completed

  27. get_tool_help

    Recorded tool call · completed

  28. get_tool_help

    Recorded tool call · completed

  29. get_tool_help

    Recorded tool call · completed

  30. Progress update

    Expectation before the trial: the Canada filter should produce the supplied Canada polygon, the distance step should keep every lake row and original geometry while adding a projected boundary-distance field, and only lakes with distance `< 10000` should reach the selected output. Missing or empty original lake geometry should stay unselected and be countable as unknowns through null distances.

  31. run_trial

    Recorded tool call · completed

  32. Progress update

    The first trial was blocked by a brief argument issue, not by the data or method: the saved study bbox was recorded as text instead of numeric coordinates. I’m correcting that extent and retrying the same method.

  33. update_analysis_brief

    Recorded tool call · completed

  34. Progress update

    The trial finished in the background. I’m inspecting the actual Canada filter, distance output, and selected lakes now so I can confirm the method before I save the production result.

  35. get_trial_report

    Recorded tool call · completed

  36. Progress update

    I’ve confirmed the preliminary counts from the trial. Next I’m checking the actual selected features and the measured distance field so I can verify that original lake rows were preserved and Canada’s full polygon boundary was the target.

  37. inspect_artifact

    Recorded tool call · completed

  38. inspect_artifact

    Recorded tool call · completed

  39. inspect_artifact

    Recorded tool call · completed

  40. inspect_artifact

    Recorded tool call · completed

  41. inspect_artifact

    Recorded tool call · completed

  42. inspect_artifact

    Recorded tool call · completed

  43. Progress update

    The earlier inspections were still finishing when the turn was interrupted. I’m reopening those exact inspections now and then I’ll save the production workflow from the tested method instead of rebuilding it.

  44. Progress update

    The method itself looks right so far: one Canada multipolygon, 13,135 lake rows kept through the distance step, and 581 selected rows with unique `benchmark_row_id`s. I’m checking the distance step’s own summary once before I lock the workflow, mainly to see whether it reports any make-valid repairs.

  45. inspect_workflow_results

    Recorded tool call · completed

  46. assess_trial

    Recorded tool call · completed

  47. Progress update

    The trial answered the main method question: it used the exact boundary-distance settings you asked for, repaired 5 invalid lake polygons for measurement only, found 0 unknown geometries, and selected 581 unique original lake rows with distances all below 10 km. I’m recording that trial and saving the production workflow from this tested computation now.

  48. update_analysis_brief

    Recorded tool call · completed

  49. get_tool_help

    Recorded tool call · completed

  50. get_tool_help

    Recorded tool call · completed

  51. Progress update

    I’ve got a tested full-area method now, so I’m saving a production draft from that exact computation rather than rebuilding anything. It will deliver the inspectable selected lakes plus the supporting one-row count tables I need for the final answer object.

  52. propose_workflow

    Recorded tool call · failed

  53. Progress update

    The draft was close. Blue flagged one exact wiring choice because the measured distance branch also feeds the unknown-geometry check. I’m correcting that binding to point at the selected-lakes branch, not changing the science.

  54. propose_workflow

    Recorded tool call · completed

  55. Progress update

    The saved workflow is valid and matches the tested computation. I’m running that exact revision now and then I’ll inspect the final selected artifact and one-row counts before I record the answer.

  56. execute_workflow

    Recorded tool call · completed

  57. inspect_workflow_results

    Recorded tool call · completed

  58. Progress update

    The final saved workflow finished in the background. I’m inspecting its three delivered outputs now so I can bind the selected artifact and the final one-row counts to the answer object.

  59. inspect_artifact

    Recorded tool call · completed

  60. inspect_artifact

    Recorded tool call · completed

  61. inspect_artifact

    Recorded tool call · completed

  62. inspect_artifact

    Recorded tool call · completed

  63. Progress update

    The last inspections were still finishing when the turn was interrupted. I’m reopening the exact final previews now, then I’ll record the final answer object from the completed outputs and their counts.

  64. inspect_artifact

    Recorded tool call · completed

  65. inspect_artifact

    Recorded tool call · completed

  66. inspect_artifact

    Recorded tool call · completed

  67. inspect_artifact

    Recorded tool call · completed

  68. inspect_workflow_results

    Recorded tool call · completed

  69. Progress update

    I have the final selected artifact and both final count tables. I’m pulling one last compact receipt from the final distance step so the final assessment cites the actual EPSG:3978 boundary-distance settings and repair count from the completed run, not just the trial.

  70. Progress update

    I’ve verified the final selected artifact, the final one-row count tables, and the final distance-summary settings from the completed run. I’m recording the accepted result now with the explicit selected artifact identity the app asked for.

  71. assess_result

    Recorded tool call · completed

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